Dogs were allowed to self-select from two diets varying in protein and carbohydrate. Energy intake averaged 1300 kcal per day and protein intake averaged 30% of energy intake. Energy in dogs is influenced by the level of fat in the diet and the level of nonprotein energy (carbohydrate or fat) influences self-selected protein intake in rodents. We therefore allowed dogs to self-select from two diets varying in protein and fat. Under these conditions neither energy intake nor protein intake differed from that of dogs fed the diets varying in protein and carbohydrate. Dogs are able to regulate energy and protein intake.